9408927, PI-NEPSTAD: Secondary forests are the by-product of increased human clearing and utilization of land in the tropical regions of the Americas. The limited time duration in which much of this land can be kept in agriculture or pasture causes much of this land to revert to secondary forest. Much remains to be learned about the formation and structure of these secondary forests. Leafcutter ants are found to be incident at 10 to 100 fold higher numbers in secondary forest compared to primary forest. They play important ecological roles in defoliation of selected tree species and as modifiers of physical and chemical nature of the soils. This project investigates the biogeochemical influence of cutter ants by characterizing nest sites, soils, and tree growth at sites with and without ant populations. This research is important because it considers the role of the dominant herbivore in these ecosystems which are recovering after human utilization and abandonment. Belowground processes in the soils of tropical ecosystems are major controls on the recovery of these ecosystems after disturbance. The leafcutter ant may well play a crucial role in improving soil conditions to facilitate forest re-establishment. This research will begin to address this potential interaction, and test the hypothesis that this prolific invertebrate enhances tree growth in these transitional ecosystems.
